


The Great Green Beast

by hades_bitch



Category: Naruto
Genre: A little bit of plot, ANBU Hideouts Used Wrong, Anal Fingering, Anal Sex, Bottom Hatake Kakashi, But mostly porn, Canon-Typical Ninja Violence, Feral Gai, Hunt and Chase of Prey, Kakashi Just Helping A Friend Out, Liberal Amounts of Growling, M/M, Multiple Orgasms, Prey Being Kakashi, Rough Sex, So Are The Trees, The gloves stay on during sex, What The Green Beast Really Is, but he likes it
Language: English
Status: Completed
Published: 2020-08-23
Updated: 2020-08-23
Packaged: 2021-03-06 14:10:41
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings, Graphic Depictions Of Violence
Chapters: 1
Words: 3,363
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26040130
Author URL: https://archiveofourown.org/users/hades_bitch/pseuds/hades_bitch
Summary: Kakashi knows mostly all about his best friend. He knows about Gai's... other personality, but he's never really experienced it. Of course, he and Gai have played around yes, but not while the Beast is out.
Relationships: Hatake Kakashi/Maito Gai | Might Guy
Comments: 9
Kudos: 161





	The Great Green Beast

**Author's Note:**

> No Explainton I just wanted feral Gai and Kakashi. Just practicing fighting scenes and porn. Tell me how I did!  
> Big thanks to [Maiika](https://archiveofourown.org/users/Maiika/pseuds/Maiika) for looking this over!  
> Any mistakes left are my own.

Gai and Kakashi flow around each other like water serpents, both in perfect sync that you only get from working with someone forever. They both have their lives in the others’ hands, as Kakashi cuts the arm off of the ninja that tries to stab Gai in the back. They just finished with an already hard mission, and these missing ninjas come out of nowhere. If they were smart, they should have run away as Gai and he have made their reputations known to the ninja world for years now. They are practically “ _Flee On Sight,”_ according to the Bingo Books.

Gai roundhouses a woman in the back of the head, flinging her face-first into a tree, the spruce falling, the woman not moving. A missing ninja jumps on Gai’s back while Kakashi is distracted, tearing open his green spandex but not drawing blood. Gai launches high into the air and slams back down on the ground, back first, the missing-nin like a cushion. 

They finish off the remaining ones, the adrenaline from their original mission and the fight they just had is high, and Kakashi sees Gai stop in the middle of the destruction, just staring at him, like a wolf seeing its last meal.

“Hey, Gai, are you good? Did that missing-nin get you on your back? Turn around, let me see-” he says as he walks toward Gai but stops in his tracks when Gai growls at him.

_Gai just growled at him, Kakashi Hatake._

At that sound, Kakashi stops midstep, not knowing what to do, why his friend is acting like- ‘ _ah that’s right. How could I have forgotten?’_

“Hey, Gai is it true that you have a Beast in you? Is that why they call you the Great Green Beast of Konoha?” Questions Kakashi, narrowing his eye at him.

Gai bears his pearly whites, but not in the way he usually does when smiling at him. Kakashi knows there is an ANBU hideout close nearby, and if he can make it, he can activate the barrier, and Gai can go wild in the forest and not on him. He just wants to sleep after this. Thinking he can make it, Kakashi dashes toward the direction of the hideout, taking the shortest route. Dodging through tree branches, but he can already feel Gai closing in on him already.

‘ _Damn, he doesn’t want to fight his best friend.’_

_‘There!’_ He can see the hideout in his view, but something crashes into his blindside, pushing him into a tree, but it doesn’t hurt as much as it should. Gai has him caged in with his muscular arms on both sides of his head, against the tree. Gai is breathing heavily and Kakashi can feel his body heat, even though they aren’t touching.

Gai shakes his head back and forth and snarls, and backs away from him, now pacing in front of him. Kakashi can see that he is trying his hardest not to tear something apart.

‘ _Maybe he can direct that energy somewhere else?’_

“Do you need something, Gai? Why did you attack a comrade?” He uses his ANBU captain voice, but Gai does not like that as he stops pacing, looks at him, and growls even louder.

“I am trying my best not to kill you, tear you apart, Rival but, you are pushing a line with the way you are talking to me.” He hisses in a deep baritone.

“Well... if you need a release maybe, you could do it in another way than killing everything in sight.” Kakashi alludes to what he wants to do with all that energy.

“There... there is something. But I would not ask that of you, Kakashi.” Gai speaks softly, despite trying to control himself, and for once, he will not make eye contact. Kakashi feels a brief tightening in his chest, but he shows no outward sign of his concern.

“Gai, you know you can ask me for anything. There isn’t anything I wouldn’t do, so long as it prevents us from sending you on dangerous missions, or tearing up a poor forest.” Kakashi is reasonably sure he already knows what else they can do. And Kakashi is not often wrong. It’s what makes him a genius. Sighing, he undoes the bandages on his legs and takes off his weapons pouch. He can feel Gai’s gaze on him as he sets his weapons aside, and he goes ahead and removes his mask and headband as well, laying them beside his weapons on a rock.

“I’m willing if you are.” Kakashi slowly unzips his jacket, creeping closer to Gai but gives the shaking man space.

“We are the only ones here, Gai. We don’t have to act as we’ve never done this before.” Kakashi, now maskless, showing his smirk despite himself, and feels better when he saw that Gai had managed to crack a small smile too.

“I think your writer friend would be upset if he knew,” Gai slides his headband off and drops it. “For as much as he writes raunchy books, I think he’d be interested in watching the things I have done to you.”

Kakashi manages a short laugh before Gai is on him, having darted from across the field, pushing back to the tree. Gasping in surprise, Kakashi places his hands on Gai’s waist just as he pinned him, and presses their lips together in an intense kiss. Kakashi has no issue with a hard and fast romp, especially when he and Gai would undoubtedly have other times to take this slower.

“Oh, you are the most honorable Kakashi.” Gai purrs, kissing down Kakashi’s pale neck. Skilled hands went to the zipper holding Kakashi’s pants up, not even bothering with the upper body flack armor. Kakashi takes the hint, kicking his feet out, flinging his sandals off somewhere. Gai wastes no time, pushing down Kakashi pants and grabbing his ass, large hands giving a firm squeeze to each cheek.

“Fuck, Gai.” Huffs Kakashi, clutching at the torn spandex, still covering his back. “Tell me, tell me what you need to get it out there.” 

He stutters a little as Gai kisses his neck. As much as he trusted Gai, having him in this state, his jugular bared was still setting off alarms in the back of Kakashi’s brain. Shinobi training made you used to be the predators, not the prey.

“You’re afraid,” Gai murmured but didn’t pull back. Kakashi, knowing he would not be able to hide it, nodded. “I need that,” Gai sounded a little ashamed as he spoke. “I need... not just the lust. The bloodlust, prey drive, I need to bring that out, to satisfy it.”

Kakashi nodded, accepting it readily. He trusts Gai far too much to be truly afraid, but he understands his role right now. He tilts his head to the side, showing Gai more of his neck. The submissive display did something for the Beast, who immediately nosed against Kakashi's throat, a sound that was nearly a growl, as he mouthed over Kakashi’s pulse point. His hands stayed on Kakashi's ass, gripping tightly and pulling him forward. Even through the layers of clothes, Kakashi could feel Gai's already hard cock. He curses under his breath, giving a quick tug to Gai's torn spandex.

“There’s oil, in my weapons pouch, it’ll work,” Kakashi manages to get the words out without stuttering, but he already sounds like he’d been fucked. Gai was pleased, pulling back enough to be able to look Kakashi in the eye.

“Turn around." Gai’s voice carried an authority that even Kakashi wasn’t going to question. As soon as Gai stepped back, Kakashi turned to face the trunk of the tree. He braced himself against the tree, leaned forward and stuck his ass out intentionally. Kakashi feels exposed and aroused, a thrill running through him he couldn’t quite put his finger on. When Gai returns, he has taken off his leg warmers, vest, and the rest of his spandex. Kakashi had a brief moment to admire his speed before Gai is on him again, pushing his flack collar off his neck and kissing him there.

“You always were so good for me. I hadn’t forgotten that, Kakashi.” Gai murmured, his hot lips still on the back of Kakashi's neck. Kakashi shivered, feeling Gai grip his ass and spread him open. The drip of cold oil between his cheeks made Kakashi clench his jaw in anticipation, and he gasps a little when he feels Gai's finger rubbing over his hole.

“Relax, Kakashi.”

Kakashi nodded and did as told, closing his eyes and resting his forehead against the tree. Gai was careful as he eased a finger into him, holding him spread open with his other hand. Kakashi grunts quietly at the initial intrusion but is quieted by Gai's lips on the back of his neck again. Gai had always been an attentive lover in the past, and Kakashi didn’t expect that to change. When Gai plunges a second finger alongside the first, Kakashi pushes back to meet him, making the man chuckle.

“Needy much?" Gai whispers in Kakashi's ear, thrusting his fingers in and curling them forward as he drew back. Kakashi chokes on a moan, his legs tensing for a moment. 

“Right there?” Gai asked, pressing against the same spot again, making Kakashi shake.

“You know you won’t break me." Kakashi impatiently huffs, as Gai rocks his fingers in and out, scissoring them gently as he adds a bit more oil. Gai shakes his head, almost laughing.

“I have always admired how honorable you are, Rival. Truly a part of the Fountain of Youth, the Well of Spring-”

“Gai, now is not the time for your speeches.” Kakashi cut the man off with a hiss, managing to toss a glare over his shoulder. Gai looked more amused than threatened, but then again, Kakashi did not pose a threat to him in any way, at the moment.

“Very well, then.” Gai steps back, looking down to watch as his fingers slide out of Kakashi. He always loved watching, Kakashi recalls. But as he had said, now is not the time. Reuniting sexually, as fun as this is, they are doing this for a purpose. Kakashi can hear the sound of him rubbing the oil over the length of his cock, and wonders if Gai plans on taking him just like this. It definitely wouldn’t be the first time.

Kakashi got his answer a few moments later when Gai spins him around. He puts both of his big hands on the back of Kakashi’s thighs, the taijutsu master lifting the lean copy ninja, and presses his back against the tree’s rough bark. Kakashi had very nearly forgotten what it was like to be handled like this, as Gai was the only person he’d been with who was strong enough to pull it off.

“Kakashi.” Gai hums his name, encouraging Kakashi to wrap his legs around his waist, slinging his arms around Gai, clinging on to him, leaning on the trunk behind him for support. He could hardly register that Gai was holding him up with one arm when he felt the blunt head of Gai’s cock pressing against his hole.

“Oh fuck,” Kakashi shivered as Gai began to push in, breaching him with just the head of his cock at first. Gai is thick, and Kakashi savors the sting as he is stretched open. Gai begins to mouth over Kakashi’s jaw and throat as he pushes in the rest of the way, sliding in a few inches before drawing back and starting over again. It’s sweet torture for Kakashi, and he absently wonders if this is Gai’s replacement for not being able to torture himself the way he’d originally planned.

Gai lets out a slow exhale against Kakashi’s skin as he bottoms out, his hips pressed firmly against the others’ ass. Kakashi is already panting softly, his cock neglected and weeping pre-cum between them. Kakashi can feel the way Gai was holding himself back as he drew back, thrusting back in at a sturdy pace. As good as it felt for Kakashi, being filled and feeling the drag of Gai’s cock against his prostate, he knew it wasn’t enough.

“Come on,” Kakashi runs a gloved hand through the short black hairs at the back of Gai’s head, giving them a sharp tug. The tug makes Gai snap his hips forward, forcing a moan from Kakashi. “Don’t- don’t hold back, Gai, come on, fuck me.” Kakashi could hear the frustration in his voice, and Gai’s responding growl told him that he’d done well.

Gai shifts his grip on Kakashi quickly, holding on to him tightly before pulling nearly out. Kakashi has time to take in one breath before Gai slams his hips forward, fucking into Kakashi so hard that his whole body lifts. Kakashi cries out wordlessly, dropping his head back against the tree behind him as Gai fucks into him over and over, brief and harsh thrusts that never missed his prostate. Kakashi is incredibly turned on by the show of strength, as Gai all but bounces him on his cock, growling into his throat as he does. Gai is pure muscle from all the training he does. The perks of being Konoha's resident taijutsu master, and Gai being able to move him like a sack of flour, makes Kakashi’s cock twitch.

“Gai, shit, yes.” Kakashi gasps out, clenching his still gloved hands tightly on Gai’s back, feeling the muscles ripple across, as he continues to thrust into Kakashi with a force that the smaller man knew he’d be feeling the next day. Kakashi wraps a hand around his cock, feeling Gai growl out again when he moved. The growling sounds were becoming steadily more bestial, which should not have added to Kakashi’s arousal as much as it did. Stroking himself off quickly, Kakashi turns his head to the side, exposing his neck in a further sign of submission. The next growls that left Gai reverberated through Kakashi’s chest, and he almost came right then and there.

Gai must have felt Kakashi tighten around him because he started to fuck even more earnestly, and Kakashi didn’t think that is possible. It’s only a few more moments before Kakashi groaned through clenched teeth, clamping down on Gai’s cock as he came. A snarl leaves Gai’s lips as he buries himself fully in Kakashi and stops, letting Kakashi’s insides tighten and flutter around him as he rode out his high. When Kakashi comes down, he didn’t have time to be frustrated at the mess on his shirt. It’s a good thing the ANBU hideout next to them has clean clothes. Gai pulls out of him slowly, carrying Kakashi over to a patch of soft moss.

“On your hands and knees.” Gai hisses, setting Kakashi down gently. He does so, resting on his forearms and holding his ass high, presenting himself. It was incredibly exposing, but Kakashi needed to get Gai as worked up as he could.

Gai and Kakashi both moan when he enters again, one hand splayed on his lower back as the other guided his cock inside. Kakashi is panting, thrusting back against Gai to get him to go even faster. Growling again, Gai moves his free hand to the back of Kakashi’s neck, pinning him face down into the moss, his arms falling beneath him, while Gai buries his cock fully inside. Kakashi groans, tearing at the soft moss below him, as Gai begins fucking into him mercilessly. He can feel how Gai’s temperature rises higher and higher. He feels like he is burning his insides.

“Fuck!” Kakashi shouts when Gai angles his hips differently, dragging the fat head of his cock over Kakashi’s prostate every time he thrusts back into him. Kakashi is in a completely different position, and he wasn’t sure Gai would even let him touch his cock. The stamina that he has meant he hadn’t even gone soft yet, his cock still hanging heavily between his legs, bouncing from the force Gai is using to thrust into him.

“Right fucking there, Gai.” Kakashi slurs, earning himself another low and almost threatening snarl from the Beast above him.

Much to Kakashi’s surprise, he is almost sure he was going to cum again. He’d never managed to have an orgasm in all of his years without contact with his cock. And with the way Gai is fucking him, there wasn’t much doubt in his mind that this would be the first time. The Green Beast has come out to show itself and is rutting into him almost savagely, spreading Kakashi open on his cock over and over in a way that is making his head spin. Gai still has a hand on the nape of his neck, pinning him down, but his other hand was gripping on to his hip tightly, pulling him back roughly to meet his thrusts. The sounds of skin smacking against skin are audible in the little outdoor cove, and Kakashi loves it.

The rush of his second orgasm forces a cry from Kakashi’s throat, an almost pained noise that Gai’s Beast seemed to love. Kakashi didn’t spare much thought of the tighter grip on his neck and hip, much too focused on how good it feels to clench around Gai’s cock as his own twitched, spilling onto the grass beneath him. The copy ninja nearly blacks out, and he feels the moss, as Kakashi tears it out of the ground, from the force of his grip, the poor plant in pieces in his hands. 

Panting heavily, Kakashi has a hard time keeping his wits about him when Gai begins to thrust into him again, the sensitivity making Kakashi’s entire body tingle.

Gai either didn’t have the capacity to tell Kakashi that he was going to cum, or thought that growling and biting into the collar of the flack jacket, right over Kakashi’s ear would be enough of a warning. Kakashi moans when he feels Gai’s hot release finish inside him; the ragged man thrusts, stuttering to a halt. He remains buried deep inside the other ninja for a few moments, breathing heavily, before releasing his jaw’s hold on Kakashi’s flack jacket and pulling out of him slowly. Kakashi already feels the unpleasant sensation of Gai’s cum leaking out of him, but now was not the time to worry about being messy.

Looking down at himself, Kakashi decided to remove what remained of his flack jacket. He would need to replace it with the ones they have in the hideout. Gai had torn into his and had done some damage. Once he was nude, Kakashi set out to get the bedrolls out and pushed them together on the floor.

“You in there big guy?” Kakashi asks, eyeing the sight of his best friend like he was a kicked puppy in the corner. Gai stirred, and Kakashi took that to mean that he was listening. 

“When you’re done feeling guilty, you should join me. I just got fucked into the ground by the Green Beast, in the forest against a tree, there’s at least ten jokes to be made.” Kakashi lays down as he spoke, pulling the travel blankets over his bare body.

Kakashi didn’t fall asleep yet when he feels a comfortable, warm body get behind him. The arm that slides around his waist is gentle, and Kakashi sighs in relief. Gai’s grip tightens on him momentarily, and he nudges his broad nose against Kakashi’s shoulder.

“If I remember correctly, you like being held afterward.” Gai murmurs just loud enough for Kakashi to hear. He nods willingly, to admit it when it was only the two of them. “Thank you, Kakashi, my Rival, for helping me... in a more pleasant way. I know it was probably terrifying, even for a ninja like yourse-”

“Gai,” Kakashi cuts the other off “I wasn’t terrified. I just had the fuck of my life, and I’m exhausted. Just let me sleep. You need to sleep, as well. We need to get back home tomorrow.”

Gai chuckles against Kakashi’s shoulder. “Very well. All is forgiven, Kakashi. Let’s get some sleep.”

**Author's Note:**

> Hoped yall liked that. I like experimenting with different ships and tropes, and this one wouldn't leave my head. Wrote this in 2 days!  
> Thanks for reading y'all, leave a comment  
> Wash 'yer hands and feet, stay safe!


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